Insulating composition.



i; an STATES PATENT OFFICE.

MIN'DliL IN McG-ERRY,ou-K LAMAzoo, MICHIGAN, ASSIGNOR To ear ncno vntgpr I o IoAco-ILLINoIs. INsuLArrmo comrosirrom To all whom may ccncemi lfie it known that 1,..1VII'NDELIN McGrnRIiY, a citizen of the United States, residlng at Kalamazoo, in the county of Kalamazoo and State of Michigan, have invented new: in Insulating;

and useful Improvements Compositions, of which the following is .a specificatiom H The purpose ofthis invention is to provide an improved composition for coating therefore Without sacrificing any of the advantage of close winding of such armatures' The invention consists in the composltion of the insulating covering hereinafter described.

The improved insulating wire which constitutes this invention consists of a core of electrically, conducting wire, wound or otherwise covered with any customary insulating thread of textile fabric sheath, and additionally provided with composition to be hereinafter described, with which such sheath is saturated and may be also overlaid. Preferably, the composition hereinafter described is wound wire, Whether with or Without an interior insulating layer of rubber; and such textile fabric covering is useful in connection with the composition to be described without regard to the insulating character of such textile fabric, but merely by virtue of its capacity for being saturated with the composition and retaining the same incorporated with it and so constituting an inclosing sheath about the wire.

The composition which I employ comprises the following elements: (1) finely ground asbestos pulp; (2) pulverized slippery elm; (3) a vegetable acid, as vinegar; (4) glue; (5) a starchy substance, as corn starch or Wheat flour.

The asbestos contributes to the composition non-conductivity of heat. The glue constitutes the principal binder. The slippery elm modifies the hardness and infiexi- Specification. of Letters Patent, f Application filed October 5, 1908.

' an theigmg Jana;

, ture.

applied to .the usual silki311 patents hug-Q10, 1 09. seria fno. 456,255. I

' increases-the flexibility 'and* r composition when dry, as-ih ser-viceon: the wire." The 'star cliy elementf-whether corn starch or *wheat flour, also tends to"-'mod1ify the hardness" of the,composition,- but its more distinctive func covering for the wire. The vegetable acid, as vinegan to someaextentdig'ests ,or dlssolves the dry elements,

/ V I ion is to rendery, the; composit on smoother and adapt t: to; produ'ce asmooth surface and tends to render the composition -pulpy even before it is cooked as hereinafter-explained. f The mode of preparation which I have employed with the best success is as follows and the ground slippery elm about in the proport ons of3 to.2, and add enoughvmegar to th oroughly inoisten the mixture,"/but character. for a mixture consisting of 12 ounces of asbestos and 8 ounces of slippery elm will be usually about 1 pint or 16 ounces. The mass thus prepared is allowed to stand for two or three days without exposure to any more than ordinary atmospheric tempera- Thetime Will vary according to the strength of the acid employed, but this step of the process will be completed when the mass attains to a jelly-like condition if the minimum-of vinegar was used, or a ropy condition if a larger amount has been used. I then thoroughly intermix with it about 14 ounces of glue, which has first been thoroughly dissolved in water. term glue in its most generic sense, indicating any glutinous material, whether the finer or coarser sorts. Common carpenters or cabinet-makers glue, gum arabic or coarser varieties can be used, the quantity necessary varying somewhat according to the quality. The mixture with the glue added is then cooked slowly until it begins to thicken with the cooking somewhat after the manner of flour paste; and at this stage preferably a comparatively small amount of the starchy material, corn starch or Wheat flour, is added, being thoroughly stirred in, the cooking being continued long enough to cook the starch or Hour to a past-y condition. About 2 ounces of corn starch for each 12 ounces of asbestos I have found to produce a satisfactory result. WVhen thoroughly I use the I thoroughly mix' the ground 1 asbestos pulp not solias to render'it- 'the lea'st-fluid-in The quantity ofvinegar requisite:

cooled the mass is then strained through a fine sieve to take out all lumps and all fibers of the asbestos so as to produce a perfectly smooth-grained mass which can be applied to the wire in an even coating which will assume a smooth surface in dry- The proportions of the several materials used may be varied considerably without defeating the results. The glue, as already indicated, may vary according to the quality, and the variationof the quantity of the starchy element will afiect the smoothness of the product without substantially defeating its essential qualities. The quantity of vinegar may vary aceordingto its strength. The variation of the relative proportions of the slippery elm and glue will affect the hardness and flexibility, any considerable excess of slippery elm above the proportion named having the efiect to render the coating liable to scale, and any considerable diminution of the proportion of the slippery elm causing the mixture to be harder than desirable, preventing the flexibility of the wire when coated therewith; but variations amounting to not more than 25% from the relative proportions of these elements will not defeat the eificienoyof the composition for its purpose, but will only modify its properties,

such modification being permissible upon diiferent grades of wire, the larger sizes which are to be wound with a larger radius requiring less flexibility and permitting greater hardness in the coating than the finer wires which are to be wound with a small radius.

I claim 1. A composition for coating wire for insulation consisting of asbestos pulp, slippery elm, a vegetable acid, glue, starch and water.

2. A composition for coating wire for insulation-consisting of asbestos pulp, slippery elm, a vegetable acid, glue and starch dissolved in water and cooked to a paste.

3. A composition for coating wire for insulation consisting of asbestos pulp and slippery elm digested to a jelly in a vegetable acid, and mixed with an aqueous solution of glutinous and starchy material.

In testimony whereof, I have hereunto set my hand, in the resence of two witnesses, at Chicago, Illinois, this 2d day of October, 1908.

MINDELIN MCGERRY.

In the presence ofy M. GERTRUDE Any, G. S. Annor'r. 

